Frankie Valli plans to keep performing as long as he is “able”. The 90-year-old crooner has sparked health fears among fans as he’s been taped by crowds looking frail at his recent performances. But he has now told People: “I know there has been a lot of stuff on the internet about me lately so I wanted to clear the air. “I am blessed to be 90 years old and still be doing what I love to do and as long as I am able, and audiences want to come see me, I am going to be out there performing as I always. “I absolutely love what I do. “And I know we put on a great show because our fans are still com…